But in your scenario they are an integral and necessary part of the device, so it's costed in.

In a television it's an added cost and it's unclear if serving ads really can offset that extra $25-100 of hardware (and included data) you ship on a $200-1000 television.

It's also unclear to me if the low data packages they come with would be enough to serve meaningful ads to begin with. Those devices usually come with a fixed plan of 100MB/month for 5yrs (or along those lines). Modern smart tv ads are very often video or at least hi res images.